The present invention relates generally to a vibration generator and more particularly to a vibration generator which is especially, but not exclusively, suitable for use with vibratory conveyors and vibratory screens.
It is known to provide vibration generators of this general type where a first imbalanced mass is mounted on the output shaft of a motor for rotation with this output shaft, and a second imbalanced mass rotates with the first mass and is shiftable radially away from the output shaft under the influence of centrifugal force and against the force of prestressed springs. Both the first and the second imbalanced mass are in form of relatively massive steel members, and the second imbalanced mass is guided by four bolts which are strongly enough dimensioned so as to be able to reliably withstand the relatively high forces which develop in the operation of the vibration generator.
This prior-art construction has certain disadvantages. Because of the rather massive construction of the various involved components, the necessity for providing the springs and necessity for providing the guide bolts, which all also add to the total mass to be accelerated, this total mass is rather large so that the electromotor which drives the generator must overcome a large starting moment, thus making it necessary that a motor be used having a high starting torque and which is correspondingly expensive. An additional disadvantage of this prior-art construction resides in the fact that the guide bolts which guide the second imbalanced mass during its movements relative to the rotary shaft are subject to quite significant wear, so that over a period of time undesirable noises will develop during the operation of the vibration generator. Moreover, these guide bolts must of course be frequently lubricated.